If the length is a, the width is b and the height is c, then

The length is increased by 2 cm, and the volume is increased.

2bc= 15, in the same way.

3ac=30，

4ab=48, what's the solution? ab= 12，bc=7.5，ac= 10

What is the surface area? 2(a b+ BC+AC)= 2( 12+7.5+ 10)= 59

(Note: Specific values of A, B and C are not required)

The second question: If the side of this cuboid is square, we can know that the height of the cuboid is four times the side length of the square at the bottom (see the figure for details).

The side length of the square at the bottom of a cuboid is 6/4= 1.5, so its height is 1.5*4=6, and its volume (volume).

v = 1.5 * 1.5 * 6 = 13.5

The cardboard area required for making 1 rectangular box is

s = 1.5 * 1.5+4 * 1.5 * 6 = 38.25？ (Note: There is no cover, only the bottom edge is needed to calculate the area. )

Therefore, the cardboard required to make 10 rectangular boxes is 382.5 square centimeters.